I’ve been digging into the NumPy C API docs, but I’m stuck on something. Is there a way to create an actual matrix object, not just a 2D array? Here’s why I’m asking:
My function deals with math matrices, and I want to avoid weird results if someone forgets to change an array to a matrix before doing matrix multiplication or exponentiation. Those operations are the main differences between arrays and matrices in NumPy.
I know how to make arrays with the C API, but I can’t find anything about creating true matrix objects. Am I missing something obvious? Or is this not possible with the C API?
If anyone has experience with this or knows a workaround, I’d really appreciate some guidance. Thanks!
Creating a true NumPy matrix object using the C API isn’t straightforward, as matrices are essentially a specialized subclass of ndarray. The C API primarily deals with arrays, not higher-level Python objects like matrix.
A workaround could be to create a 2D array using the C API, then use PyArray_Return to get a Python object. From there, you could call the matrix constructor in Python code. This method involves some Python interaction, which might not be ideal for performance-critical code.
Alternatively, you could implement matrix-specific operations yourself in C, ensuring proper behavior for multiplication and exponentiation. This approach gives you more control but requires more work.
Ultimately, the best solution depends on your specific use case and performance requirements. If you’re dealing with large datasets, sticking with arrays and implementing careful checks might be more efficient than using matrix objects.
As someone who’s worked extensively with NumPy’s C API, I can tell you that creating a true matrix object directly through the C API isn’t really possible. The matrix class is more of a Python-level construct.
However, I’ve found a workaround that might suit your needs. You can create a 2D array using the C API, then set a flag to make it behave more like a matrix. Here’s the general idea:
Create your 2D array using PyArray_SimpleNew or similar functions.
Use PyArray_ENABLEFLAGS(arr, NPY_ARRAY_F_CONTIGUOUS) to ensure Fortran-contiguous memory layout.
Set the NPY_ARRAY_WRITEABLE flag to false to mimic matrix immutability.
This approach won’t give you a true matrix object, but it will result in an array that behaves similarly for many operations. Just remember to handle matrix multiplication and exponentiation carefully in your C code.
If you absolutely need matrix behavior, you might have to wrap your C function in Python to convert the array to a matrix after creation. It’s not ideal for performance, but it guarantees correct matrix semantics.
hey there, i’ve run into this issue before. sadly, creating a true matrix object via the C API isn’t really doable. matrices are more of a python-level thing.
but here’s a trick - you can make a 2D array act kinda matrix-like: